Rotary indexing fixture



Feb. 12, 1952 A. H. PEARSON ROTARY INDEXING FIXTURE 7 Sheets-Sheet 1 Filed Feb. 18, 1946 IN V EN TOR. 4/017 H Pearson @6232? )f alldlw ATTORNEYS A. H. PEARSON ROTARY INDEXING FIXTURE Feb. 12, 1952 7 Sheets-Sheet 2 Filed Feb. 18, 1946 INVENTOR. A/an hi-Pearson BY ,@mmm w% b A TIER/V575 '7 Sheets-Sheet 5 Filed Feb. 18, 1946 1952 A. H. PEARSON ROTARY INDEXING FIXTURE 7 Sheets-Sheet 5 INVENTOR. Alan H. 1 60/60 w raw H770 Nfyi Filed Feb. 18, 1946 Feb. 12, 1952 A. H. PEARSON ROTARY INDEXING FIXTURE 7 Sheets-Sheet 6 Filed Feb. 18', 1946 INVENTOR. Alan H. Pearson Feb. 12, 1952 A. H. PEARSON 2,585,828

ROTARY INDEXING FIXTURE Filed Feb. 18, 1946 7 Sheets-Sheet 7 INVENTOR. A/an H. Pea/"Jon A 7' TORNEYJ Patented Feb. 12, 1952 ROTARY INDEXING FIXTURE Alan H. Pearson, Detroit, Mich., assignor to Pearson, Inc., Detroit, Mich., a corporation of Michigan Application February 18, 1946, Serial No. 648,463

Claims.

The invention relates generally to indexing fixtures and refers more particularly to improve ments inindexing fixtures having a rotary Work supporting table.

One of, the. objects of this invention is to provideo an indexing, fixture having means for locating, the table in any one of a number of angular positions of adjustment in accordance with the law ofsines. The sine-bar method of measuring or determining angles has long been recognized as, extremely accurate and the design as well as the. construction of the fixture is such as to take full advantage of. this accuracy.

Another object of this invention is to provide means for firmly clamping, the table in any one of its, angular positions of adjustment by exerting the clamping force in such a manner that it does not. interfere with the accuracy of the table setting regardless of the magnitude of this force, In accordance with, this invention, the

clamping forceis substantially uniformly applied.

the driving, means therefor, and as a result, may :i

be. freely rotated to approximate predetermined locations without the necessity of operating through the usual reduction gearing provided. This arrangement saves. considerable time in initially setting the table where the latter must be. rotated, throughout a substantial distance to approach. the desired setting.

Still another object of this invention is to provide. an indexing fixture having means for locating the. table. to predetermined angular positions. withoutv the necessity of making mathematical computations and without the necessity of. attempting to manipulate the Vernier dials usually associated with the hand wheels, In general, the table. is accurately located by supporting a gage bar beneath the rotatable member of the table for selective abutting engagement with gage pins predeterminedly positioned on the rotatable member of the table adjacent to the periphery of the. latter. The gage bar is supported in a suitable holder and is set in accordance with the, law of sines, so that the table is accurately positioned.

A still further object of this, invention is to provide an. indexing fixture of' the above general type with means responsive to disconnecting the table from the driving means to move the gage bar laterally out of the path of travel of the gage pins so that the table may be freely rotated without interference from the gage bar.

The foregoing as well as other objects will be made more apparent as this description proceeds, especially when considered in connection with the accompanying drawings, wherein:

Figure 1 is a front elevational view of an indexing fixture embodying the features of this invention;

Figure 2 is a plan view, partly in section, of the fixture shown in Figure 1;

Figure 3 is a sectional view taken substantially on the plane indicated by the line 33 of Figure 2;

Figure 4 is a sectional view taken substantially on the plane indicated by the line t-t of Figure 2;

Figure 5 is a sectional view taken substantially on the plane indicated by the line 55 of Figure 2;

Figure 6 is a sectional view taken on the plane indicated by the line 6-6 of Figure 2;

Figures '7, 8, 9 and 10 are respectively sectional views taken on the lines 'l1, 8--8, 9-9 and I0-H.l of Figure 3;

Figure 11 is a sectional view taken on the planeindicated by the line I l! l of Figure 2; and

Figure 12 is a sectional view taken on the line l2-|2 of Figure 3.

The indexing fixture selected for the purpose of illustrating this invention comprises a base It and a work supporting table it supported on the base for rotation about a vertical axis. The base 15 has a central opening therethrough for receiving a hub H projecting downwardly from the table in concentric relation to the axis of the table and journalled in a pair of roller bearings l8 and is spaced from each other axially of the hub I1. The top bearing I8 is of sufiicient diameter to support the table adjacent its periphery and the bottom bearing I9 may be somewhat smaller in diameter. However, both bearings are made to very close tolerances and are of the size required to assure true running of the table regardless of the load distribution on the table.

The table it is rotated by a hand wheel 29 through suitable reduction gearing comprising a worm wheel 2| and a worm 22. The worm wheel 2| is freely rotatably mounted on the hub IT in meshing relation with the worm and the latter is secured to a shaft 23 journalled on the base l5 in the manner shown in Figure 4 of the drawings. A spur gear 24 is secured to the outer end of the shaft 23 in meshing relation with a relatively small pinion 25 secured to the hand wheel shaft 26. This gearing affords a further reduction between the hand wheel 20 and the table H3. The total reduction is determined to effect a rotation of the table throughout one degree of travel for each complete revolution of the hand wheel. A still finer adjustment of the table may be obtained by the mechanism shown in Figure 11 of the drawings. This mechanism comprises a hand knob 21' secured to one end of a shaft 21 suitably journalled in a housing 28 and having a worm gear 29 secured thereto. The worm 29 meshes with a worm wheel 30 freely rotatably supported on the shaft 26 and selectively connected to the shaft 26 by a spreader 3|. As shown in Figure 11 of the drawings, the spreader 3| is in the form of a split ring mounted on the shaft 26 within a central opening formed in the worm wheel 33 and having cam surfaces at the ends thereof engageable with corresponding cam surfaces formed on the outer end of a cam or pin 32. The pin 32 is slidably supported in a bore formed in the shaft 26 with its axi extending radially of the axis of the shaft 26 and the inner end of the pin projects into bore 33 extending axially of the shaft 26. A plunger 34 is slidably supported in the bore 33 and the inner end of the plunger is formed with a forty-five degree chamfer engaging a correspondingly inclined surface on the radially inner end of the pin 32. The shaft 26 is provided with a threaded counterbore at the outer end for threadably receiving the inner end of a shaft 35 having a hand knob 36 fixed to the outer end thereof.

The knob 36 is positioned at the outer side of the hand wheel 20 for convenient manipulation. The construction is such that when it is desired to provide a micrometer adjustment of the table I6, the operator merely rotates the hand knob 36 in a clockwise direction to thread the shaft 35 into the counterbore sufiiciently to engage the inner end of the shaft 35 with the adjacent outer end of the plunger 34. As a result, the plunger is moved inwardly and the pin 32 is moved radially outwardly to spread the ring 3| into frictional contact with the inner surface of the worm wheel 30. Thus, the worm wheel 30 is connected to the shaft 26 and rotation of the shaft 2'! by the hand knob 21' rotates the shaft 26 at a reduced speed. Inasmuch as the shaft 26 is connected to the shaft 23 by the reduction gearing 24 and 25, and since the worm 22 on the shaft 23 meshes with the worm wheel 2|, it follows that the latter is rotated at an extremely slow rate by the hand knob 21'.

It has been stated that the worm wheel'2| is freely rotatably supported on the hub ll of the table l6. Thus, in order for the worm wheel 2| to effect rotation of the table l6, it must first be connected to the table. As shown in Figure 3 of the drawings, this is accomplished by expanding a split band 38 in frictional engagement with the worm wheel 2|. In detail, the worm wheel 2| is formed with an upwardly extending annular flange 39 having an inner cylindrical surface 43 concentric with the axi fo rotation of the table Hi and the band 38 is supported within the flange for engagement with the cylindrical surface 40.

The band is connected to the hub H of the table l6 by a plunger 4| slidably supported in a bore 42 formed in the hub ll with its axis extending radially with respect to the axis of on the inner end of the rod 6|.

rotation of the table. One end of the plunger 4| is formed with converging cam surfaces 43, respectively engageable with correspondingly inclined surfaces 44 on adjacent ends of the band and normally urged in a direction away from the ends of the band by a coil spring 45 surrounding the opposite end 46 of the plunger 4|. The end 46 of the plunger 4| is located in a counterbore 47 and a stop washer 48 having a diameter greater than the diameter of the plunger is secured to the end 43 by a fastener element 49. Thus, the stop washer 48 cooperates with the base of the counterbore 41 to form axially spaced shoulders 5| and 52. The coil spring 45 surrounds the plunger between the shoulders and normally holds the plunger 4| in a position wherein the band 38 is collapsed or, in other words, is out'of frictional contact with the surface as on the gear 39.

The plunger 4| is moved against the action of the spring 45 in a direction toward the band 33 to expand the latter into frictional contact with the cylindrical surface 40 on the ring gear 2| by a push rod 53. The push rod 53 is supported for sliding movement in a bore 54 formed in the hub ll of the table in concentric relation to the axis of rotation of the table. The upper end of the bore 54 intersects the bore 42 and the corresponding end of the push rod 53 is fashioned to provide a flat portion 55. As shown particularly in Figure 10 of the drawings, the flat portion 55 projects into a slot 56 formed in the plunger 4| and is fashioned with an inclined cam face 51 for engagement with a correspondingly inclined cam face 58 on the adjacent wall of the slot 56. The lower end of the push rod 53 is formed with a conical portion 59 adapted to be engaged by an inclined cam face 60 formed on the inner end of a second push rod 6|. The outer end portion of the push rod 6| extends through a bore 62 formed in the base l5 and is provided with an enlargement 63. A coil spring 63' surrounds the rod 6| at the inner side of the enlargement 63 and the inner end of the coil spring is seated on an annular shoulder 64 formed by counterboring the outer end of the bore 62. The arrangement is such that the spring 63 normally urges the rod 6| in a direction away from the rod 53 so that the rod 53 is normally in its inoperative position with respect to the plunger 4|. The extreme outer end 65 of the rod 6| engages a plunger 66 having a head 61 on the inner end slidably engageable in a counterbore 63 and having the outer end projecting into a housing 69 for engagement with a cam 16. The cam 10 is secured to a rotatable shaft journalled in the housing 69 and having a control handle 12 secured thereto.

The plunger 66 is normally urged into contact with the cam '53 by the spring 63', so that rotation of the cam by the handle 12 shifts the push rod 6| inwardly and moves the rod 53 upwardly by reason of the engagement between the conical lower end 59 of the rod and the cam face 60 Owing to the fact that the cam surface 51 on the upper end of the rod 53 engages the corresponding cam surface 58 on the plunger 4|, it follows that upward movement of the rod 53 effects a radial movement of the plunger 4| against the action of the spring 45 to engage the cam surfaces 43 on the plunger with the corresponding cam surfaces 44 on the adjacent ends of the band 38. Continued radial movement of the plunger 4| in the above direction expands the band into frictional engagement with the cylindrical surface 40 in the worm wheel 2 l, and the latter is'thereby connected to the hub ll of the table. As a result, the table may be rotated by manipulating either the hand wheel 20 or the knob 21, depending upon whether approximateor accurate adjustment of the table is required.

Referring again to Figure 3 of the drawings, it will be noted that the push rod 6! is Slidably supported in a coverplate 13 suitably secured to the base IE to form a closure for the-central opening formed in the base. A sealing gasket 14 is preferably provided between the plate 13 and the base I to prevent foreign matter from escaping into the apparatus and fouling the bearing l9. Foreign matter is also prevented from escaping into the upper end'of the central opening through the base and fouling the top hearing it by a sealing ring 15 suitably secured to the underside of the table for rotation as 'a unit with the latter and having an annular por-v tion 16 extending into the upper end of the central opening formed in the base 15. An annular groove is formed in the portion T6 and a ring H of sealing material is secured in the groove with the periphery frictionally engaging the inner wall of the central opening through the base 15.

The table may be clamped in any one of a number of angular positions of adjustment by a clamping device indicated generally by the reference character 18. The clamping device comprises a ring '59 secured to the table-l6 and having a cylindrical surface 8!! concentrically arranged with respect to the axis of rotation of the table. In the present instance, the ring "is positioned between the bearings and surrounds the annular flange 39 on the worm wheel 2!. This construction assures a compact and highly effective arrangement. In any event, a split band B! is positioned to surround the cylindrical surface 8i! and the ends of the band are res ectively formed with converging cam faces 82.

The band is contracted against the cylindrical surface 85 by means of a plunger 83 slidably supported in a bore 84 formed in the side wall of the base 15 with its axis extending radially with respect to the axis of rotation of the table. The inner end of the plunger is formed with a recess 85 and the-opposite ends of the recess are inclined or, in other words, diverge from the base of the recess to form cam faces 56. Theband 81 is angularly positioned so that the cam faces 32 on the ends thereof project into the recess 35 and respectively engage the cam faces as on the plunger 33. The radially outer end of the plunger 83 is adapted for engagement by the inner end of a shaft 81 having a hand knob 38 secured to the outer end thereof. The shaft 81 is threaded and threadabiy engages a cap 89 having an attaching flange se secured to the adjacent side of the base 55 by fastener elements 9!. Thus, by turning the hand knob 88 in one direction, the plunger 53 is forced inwardly to contract theband Bl against the cylindrical surface .130 on the ring is. Inasmuch as the ring 19 is securedto the table it, it follows that the latter is held against rotation. It is important to note that the clamping pressure applied to the table by the band is exerted radially and substantially uniformly throughout the circumference of the cylindrical surface 86, so that this pressure does not affect or disturb the position of'the table with respect to the base. The table may be readily released by merely rotating the hand knob in the opposite direction sumciently to release the clamping pressure on the band 8|.

Provision is also made for conveniently loeating work on the top of the table and this is accomplished by axially boring the table top to form a centrally located bore 92. A plug 93 is positioned at the bottom of the bore to close the latter and a bushing 94 .is secured in the bore. The upper end of the bushing is formed with a recess 95 and a plug 96 is supported in the recess to prevent chips and other foreign matter from entering the bushing. This plug may be readily removed when ity is desired to use the bushing for indicating purposes.

It has been previously stated that the table it is rotated to approximate predetermined angular positions by manipulating the hand wheel 2%]. To assist this operation, the periphery of the table is graduated in degrees, and a pointer 3'! is fixed against rotation with the table immediately adjacent the periphery to indicate the degree graduations of the table.

In order to enable accurately positioning the table in any preselected angular position, the table is provided with a plurality of gage pins 93. The gage pins are respectively mounted in bores formed in the table adjacent the periphery of the latter and are spaced equal distances from each other circumferentially of the table. Although the number of gage pins may be varied depending on the use of the table, nevertheless, for the purpose of illustration, sixteen gage pins are shown. These pins are spaced from each other throughout an angular distance of twenty-two and one-half degrees and the lower ends of the pins project below the bottom of the table for selective engagement with the inner end of a gage rod 99.

The gage rod 99 is slidably supported by a holder I00 with the axis of the rod extending as a chord of the geometric circle intersecting the axes of the gage pins 98; The holder It!) is substantially U-shaped in cross section and the top leg till of the holder is formed with a longitudinally extending groove m for slidably supporting the gage bar 99 in the above described position. The bottom leg I 03 of the holder is hinged to the base I5 by a pin H14 in a manner to enable swinging the top leg Hll from the full line position shown in Figure 3 of the drawings to the broken line position wherein it will be noted that the gage bar is located out of the path of travel of the gage pins 96.

Swinging of the holder to the broken line position shown in Figure 3 of the drawing may be effected manually by pulling the handle 05 or may be accomplished automatically in response to releasing the worm wheel 2! from the hub ll of the table by rotating the cam it to its inoperative position. In detail, the head 6'! on the plunger 66 is formed with a frustro-conical surface I06 at the inner end engageable with a corresponding surface !Gi on the lower end of a plunger I08, The plunger m8 is slidably supported in a bore H19 formed in the base 5 with its axis extending vertically and the upper end of the plunger N38 is engaged by the lower end of a coil spring ll!) having the upper end abutting the lower end of a second plunger Ill. The plunger Iii is slidably supported in a stop nut H 2 threaded in the upper end of the bore H19 and the upper end of the plunger engages the bottom leg I03 of the holder at a point spaced outwardly from the axis of the pin I04.

Thus, when the plunger 66 is held in its innermost position by the cam I0, or in other words, when the worm Wheel 2| is. connected to the table I6 by the band 38, the holder I is held in its innermost position wherein the inner end of the gage rod 99 is located in the path of travel of the gage pins 98. The holder is accurately located in its operative or innermost position by a bracket II3 secured to the base I and having pins H4 projecting outwardly therefrom into engagement with the bosses II5 on the inner surface of the base portion of the U-shaped holder. The base portion of the holder is normally urged to its broken line or inoperative position by a coil spring H6 having the inner end abutting the base I5 and having the outer end engaging the base portion of the holder. The spring H6 is not sufiiciently strong to overcome the force applied by the spring I II! when the latter is compressed between the adjacent ends of the plungers I08 and III, so that the holder is held by the spring H0 in its operative or full line position shown in Figure 3 of the drawing, regardless of the opposing force applied by the spring H9. However, when the cam I0 is rotated from the operative position thereof shown in Figure 3 of the drawings to release the band 38 from the worm wheel 2I, the plunger 65 is moved outwardly by the spring 63 and the plunger I08 is moved downwardly sufiiciently to release the tension on the spring I I0. As a result, the force exerted on the holder by the spring II6 predominates the force applied by the spring I I0 and the holder is swung outwardly to position the inner end of the gage rod 99 out of the path of travelof the gage pins 98. The table I6 may then be quickly rotated without going through the reduction gearing by applying a rotative force directly to the table. The holder remains in its inoperative position until the cam I0 is again rotated to move the plunger 68 inwardly and expand the band 38 against the cylindrical surface 40 on the worm wheel to again connect the latter to the table. As the plunger 56 moves inwardly, the frustro-conical surface I05 abuts the corresponding surface I0'I on the lower end of the plunger I08 and moves the latter upwardly. As a result, the spring III] is compressed and the plunger I II is moved upwardly to swing the holder I00 to its operative position wherein the inner end of the gage rod 99 again assumes a position in the path of travel of the gage pins 98.

As shown in Figure 2 of the drawing, when the gage rod 99 is in its operative position with the inner end engaging the gage pin A, the next preceding gage pin B assumes a position above the gage rod 99. In order to provide suflicient clearance for the gage pin B, the rod 99 is formed with a fiat 0n the top which extends from the outer end of the rod to a point adjacent the inner end. The flat portion II! of the rod 99 provides ample clearance for the gage pins 98 and is held at the top of the rod 99 by a pin II8 extending upwardly from the base of the groove I02 in the holder. The pin engages in a longitudinally extending groove II9 formed in the bottom of the gage rod, so as to permit sliding of the rod 99 relative to the holder, but to prevent rotation of the rod relative to the holder.

Supported at the outer end of the holder I00 is an elongated block I20 having a longitudinally extending V-shaped groove I2I aligned with the groove I02 or with the gage rod 99. The V-block I20 is secured to the top of an indicator housing I23, suitably secured to the base I5, and having a recess I24 beyond the outer end of the V-block I20 for supporting a dial type indicator I25. The indicator may be of orthodox design having a rotatable pointer I26 and having a dial graduated (.00005) of an inch. A suitable lock screw I2'I is provided for setting the indicator to zero reading and the pointer is connected to a spindle I28 supported in alignment with the groove I2I in the block. The spindle I28 projects through a stop bushing I29 anchored in a bore formed in an upstanding projection I30 on the indicator housing I23.

The accuracy of the various settings of the table I6 depends to a large extent on the accuracy of the spacing of the gage pins 98 around the periphery of the table and, in the present instance, a master rod C is used to calibrate or locate the gage pins. Thus, the master rod is formed to an eXact length which corresponds to the decimal equivalent of the sine of the angle between adjacent gage pins 98. As stated above, the gage pins 98 are spaced from each other throughout an angular distance of twenty-two and one-half degrees, so the length of the master rod is equal to the decimal equivalent of the sine of this angle. The master rod is engaged in the groove I2I in the block I20 with the outer end of the rod in contact with the free end of the spindle I28 on the dial indicator I25 and with the inner end of the rod adjacent the outer end of the gage rod 99. The table I6 is rotated in a clockwise direction to engage the gage pin A, for example, with the inner end of the gage rod 99. Rotation of the table in the above direction is continued by manipulating the micrometer adjustment or knob 21 until the master rod is moved into abutting engagement with the stop bushing I29 by the gage rod 99. When this condition exists, the dial indicator I25 is set to read zero by manipulating the lock screw I2'I provided for this purpose. The table I6 is then clamped by the clamp I8 and the holder I00 is swung outwardly by manipulating the handle I05 to locate the gage rod out of the path of travel of the gage pins 98. The clamp I8 is then released and the table I6 is rotated in a counterclockwise direction to locate the next adjacent gage pin B beyond the inner end of the gage rod 99. The holder is then released and is returned by the spring I I0 to again position the gage rod 99 in its operative position. When this is accomplished the table It is again rotated in a clockwise direction to engage the gage pin B with the outer end of the gage rod 99 and to engage the outer end of the master rod with the stop bushing I29. If at this time, the dial indicator reads zero, it is a known fact that the pins A and B are spaced twenty-two and one-half degrees from each other. On the other hand, if the dial indicator does not read zero, sufficient stock is removed from the pin until a zero reading is obtained. The above procedure is followed for each gage pin 98 and when completed, assures obtaining a construction wherein adjacent gage pins are spaced exactly twenty-two and one-half degrees from each other.

Assuming now that it is desired to bore a hole in a work piece clamped on the table at an angle of twenty-five degrees, twelve minutes and eight seconds, the operator merely manipulates the hand wheel 20 to rotate the table I6 throughout an angular distance somewhat greater than the above noted angle. For this purpose, the graduations on the periphery of the table in conjunction with the pointer 97 may be used. The decimal equivalent of the sine for the angle of twentyfive degrees, twelve minutes and eight seconds is then determined by consulting a table supplied with the fixture and a gage member or members are Selected having a length or a combined length equal to the decimal equivalent of the sine of the above angle. The gage members may be in the form of blocks, rods, or if desired, an inside micrometer may be used. Regardless of the particular gaging means employed, the latter is placed in the V-shaped groove l2! in the block I20 and the table It is rotated in a clockwise dimotion to engage the adjacent gage pin 98 with the inner end of the gage rod 99. Continued rotation of the table in the above direction slides the rod 99 outwardly relative to the holder int into engagement with the gaging member or members in the V-shaped groove l2! and urges the latter gaging means into engagement with the spindle I28 of the dial indicator I25. The table It is then operated by the micrometer adjusting knob 2'! to obtain a Zero reading on the dial indicator l 25 and when this is accomplished, the hole to be bored in the work piece is accurately located at the specified angle. The clamp '18 is then operated to firmly hold the table I6 in its adjusted position.

It follows from the foregoing that the sine bar principle of measurement is applied to a rotary indexing table for locating the latter in any one of a number of angular positions of adjustment. Thus, the necessity of making complicated mathematical computations preparatory to setting the table and the attendant chance of error is eliminated. Also, the usual minute and second degree graduations may also be eliminated, since the degree graduations on the periphery of the table are relied upon solely for approximate adjustments of the table and any error in such graduations does not affect the ac curacy of the table setting as is the case in orthodox indexing fixtures.

What I claim as my invention is:

1. An indexing fixture comprising a rotatable table having circumferentially spaced projections, a gage member, a holder for the gage member supported for movement relative to the table in directions to position the gage member into and out of the path of said projections, means normally urging the holder to a position wherein the gage member is located in the path of travel of the projections, driving means connected to the table for rotating the latter, means for disconnecting the driving means from the table permitting free rotation of the table relative to said driving means, and means responsiveto disconnecting the driving means to move the. holder to a position wherein the gage member is located out of the path of travel of the projections.

2. An indexing fixture comprising a rotatable table having gage pins projecting from the bottom surface in accurate spaced relationship circumferentially of the table, means for accurately locating the table in any one of a number of angular positions of adjustment including a gage bar having one end selectively engageable with the pins, a holder for said bar supported for movement in directions to position the bar into and out of the path of travel of the pins, means normally urging the holder to a position wherein the gage bar is located in the path of travel of the pins, driving means connected to the table for rotating the latter, means for disconnecting the table from the driving means, and means for moving the holder to locate the gage bar out of the path of travel of the pins in response to disconnecting the driving means from the table.

3. An indexing fixture comprising a rotatable table having circumferentially spaced projections, a gage member, a holder for the gage member supported for swinging movement relative to the table to position the gage member into and out of. the path of travel of the projections, means normally urging the holder to a position wherein the gage member is located in the path of the projections, driving means for rotating the table, releasable means for connecting the table to the driving means, and means for releasing the driving means from the table and for swinging the holder to a position wherein the gage member is located out of the path of travel of said projections.

4. An indexing fixture comprising a rotatable table having gage pins projecting from the bottom surface in accurate spaced relationship circumferentially of the table, means for accurately locating the table in any one of a number of angular positions of adjustment including a gage bar having one end selectively engageable with the pins, a holder for said bar supported for movement in directions to position the bar into and out of the path of travel of the pins, means normally urging the holder to a position wherein the gage bar is located in the path of travel of the pins, driving means for rotating the table, releasablemeans for connecting the table to the driving means including a plunger slidably. on the table, means for operating the plunger to release said driving means, and means responsive to movement of the plunger in a direction to release the table from the driving means to move the holder in a direction to position the gage bar out 7 of the path of travel of the gage pins.

5. An indexing fixture comprising a rotatable table having circumferentially spaced projections, a gage member supported in the path of travel of the projections, a holder for the gage member supported for movement relative to the table to locate the gage member out of the path of travel of the projections, driving means for the table releasable from the latter, and means responsive to releasing the driving means from the table to move said holder with the gage member out of the path of travel of said projections.

6. An indexing fixture comprising a rotatable table having circumferentially spaced projections concentrically arranged with respect to the axis of the table, a gaging element slidably supported along a path extending generally tangent to a circle intersecting the projections and having one end selectively engageable by said projections, a holder for slidably supporting the gaging element in a position to engage an adjacent projection and movable laterally relative to the table to position the gaging element out of the path of travel of the projections.

'7. The indexing fixture set forth in claim 6 in which means is provided for predeterminedly positioning the gaging element relative to the holder and thereby accurately locate the table in a preselected angular position.

8." The indexing fixture set forth in claim 6 in which the holder is pivotally supported for swinging the gaging element into and out of operative relation with said projections on the table.

9. The indexing fixture set forth in claim 6 having releasable driving means for rotating the table and having means for moving the holder to a position out of the path of travel of the projections in response to releasing said driving means.

10. An indexing fixture comprising a rotatable table having circumferentially spaced projections, a gaging element positioned to selectively engage the projections, a holder supporting the gaging element for sliding movement toward and away 'from an adjacent projection, means for locating the gaging element on the holder in different predetermined positions relative to an adjacent projection on the table to accurately locate the table in preselected angular positions, and means supporting the holder for movement relative to the table in a direction to position said gaging element out of the path of travel of said projections.

11. The indexing fixture set forth in claim in which the holder is pivotally supported to one side of the table for swinging movement from a 13. An indexing fixture comprising a rotatable table having circumferentially spaced projections, releasable driving means for rotating the table, control means for selectively connecting the driving means to and releasing the driving means from the table, a gaging element positioned to selectively engage the projections, a holder supporting the gaging element for sliding movement toward and away from an adjacent projection, means for predeterminedly positioning the gaging element on the holder to accurately locate the table in a preselected angular position, means supporting the holder for movement relative to the table in directions to respectively locate the gaging element in operative and inoperative positions with respect to the projections, means for selectively operating the holder to move said gaging means to either of said positions, and means operated by the control means for moving said holder independently of said holder operating means.

14. The indexing fixture set forth in claim 13 in which the holder is moved by the control means to locate the gaging means in an inoperative position with respect to the projections upon movement of the control means to release the driving means from the table.

15. An indexing fixture comprising a rotatable table having circumferentially spaced projections, releasable driving means for rotating the table, control means for selectively connecting the driving means to and releasing the driving means from the table, a gaging element positioned to selectively engage the projections, a holder supporting the gaging element for sliding movement toward and away from an adjacent projection, means for predeterminedly positioning the gaging element on the holder to accurately locate the table in a preselected angular position, means supporting the holder for movement relative to the table in directions to respectively locate the gaging element in operative and inoperative positions with respect to the projections, and an operative connection between the control means and holder for moving the holder upon operation of said control means.

ALAN H. PEARSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 292,140 Schefiler Jan. 15, 1884 568,006 Sweet Sept. 22, 1896 1,100,522 Brown et al June 16, 1914 1,649,411 Kaseberg Nov. 15, 1927 1,730,063 Dustan Oct. 1, 1929 1,875,739 Kearney Sept. 9, 1932 1,923,440 Hunt et a1 Aug. 22, 1933 2,329,756 Granberg et al Sept. 21, 1943 2,342,539 Gorton Feb. 22, 1944 2,364,478 Schreiber Dec. 5, 1944 2,376,137 Hallowell May 15, 1945 FOREIGN PATENTS Number Country Date 539,746 Great Britain Sept. 23, 1941 

